ackrange.h

#ifndef ACKGEN_ACKRANGE_H
#define ACKGEN_ACKRANGE_H
 
#include "common/platform/sys/syscall.h"

typedef struct {
  const u64* p; 
  usz        n; 
} u64view;

typedef struct {
  u64* p;   
  usz  cap; 
  usz  len; 
} u64obuf;
 
/* RFC 9000 19.3: an ACK frame reports the Largest Acknowledged packet number
 * and a descending list of contiguous ranges separated by gaps. This builds
 * those ranges from an ascending, deduplicated array of received packet
 * numbers (received_pns).
 *
 * Output layout (descending, matching wire order), written into ranges->p:
 *   largest          = highest received packet number
 *   ranges->p[0]     = First ACK Range length (count-1 of the top block)
 *   ranges->p[2k-1]  = Gap to the next block (RFC 19.3.1 encoding)
 *   ranges->p[2k]    = ACK Range Length of block k (count-1)
 *   ranges->len      = number of u64 values written
 *
 * ranges->cap bounds the write. Returns 1 on success, 0 if received_pns is
 * empty or ranges->cap is too small. */
int ackgen_build_ranges(u64view received_pns, u64* largest, u64obuf* ranges);
 
#endif